* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
}

body {
    background: #f2f2f2;
}

/* HEADER */
header {
    background: #CDDC39;
    text-align: center;
    padding: 20px;
}

/* MENU */
nav {
    background: #FFAB91;
    padding: 10px;
}

nav ul {
    display: flex;
    justify-content: center;
    list-style: none;
    gap: 20px;
}

nav a {
    color: #3F51B5;
    text-decoration: underline;
}

/* LAYOUT 2 CỘT */
.container {
    display: grid;
    grid-template-columns: 1fr 280px;
}

/* SẢN PHẨM */
.product-list {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
    padding: 20px;
}

.product-card {
    background: white;
    border: 1px solid #ddd;
    padding: 10px;
    text-align: center;
}

.product-card img {
    width: 100%;
}

.product-card a {
    text-decoration: none;
    color: black;
}

.product-card h2 {
    margin: 10px 0;
}

.price {
    font-weight: bold;
}

/* BUTTON */
.button4 {
    display: inline-block;
    background: #00A65A;
    color: white;
    padding: 8px 15px;
    border-radius: 4px;
    margin-top: 5px;
}

/* SIDEBAR */
.sidebar {
    background: #2196F3;
    color: white;
    padding: 20px;
}

.social-icons a {
    display: block;
    color: white;
    margin-bottom: 10px;
}

/* FOOTER */
.footer {
    background: #333;
    color: white;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    padding: 20px;
}

.footer-item h3 {
    margin-bottom: 10px;
}

/* RESPONSIVE */
@media (max-width: 900px) {
    .container {
        grid-template-columns: 1fr;
    }

    .product-list {
        grid-template-columns: 1fr 1fr;
    }

    .footer {
        grid-template-columns: 1fr;
        text-align: center;
    }
}